Method for controlling a working machine

Abstract

A method for controlling a working machine including a hydraulic system for controlling a plurality of work functions, including lift and tilt of an implement, includes the steps of determining a maximum pressure of a hydraulic fluid for performing a certain task with the implement individually for at least one of the work functions, and delivering the hydraulic fluid, pressurized at most to the determined maximum pressure, to the work function.

The invention claimed is: 
     
       1. Method for controlling a working machine, said working machine comprising a hydraulic system for controlling a plurality of work functions including lift and tilt of an implement, wherein the hydraulic system comprises at least one control valve for each function of said plurality of work functions, each control valve being actuated by a control unit, wherein the method comprises:
 determining a maximum pressure of a hydraulic fluid for performing a certain task individually for at least one of the work functions; 
 delivering the hydraulic fluid, pressurized at most to the determined maximum pressure, to said work function; and; 
 controlling the pressure of the hydraulic fluid being supplied to the work function by using said at least one control valve associated with the work function as a pressure reducer. 
 
     
     
       2. Method according to  claim 1 , wherein different maximum pressures of the hydraulic fluid are associated with at least two of the work functions, wherein the method comprises selecting the maximum pressure associated with the work function being performed. 
     
     
       3. Method according to  claim 1 , comprising determining the maximum pressure of the hydraulic fluid individually for the work function based upon the prevailing operating mode. 
     
     
       4. Method according to  claim 1 , comprising detecting at least one operating parameter and determining the maximum pressure of the hydraulic fluid individually for the work function based upon the value of the detected operating parameter. 
     
     
       5. Method according to  claim 4 , comprising detecting the operating parameter of a first work function and determining the maximum pressure of the hydraulic fluid for a second work function. 
     
     
       6. Method according to  claim 4 , comprising detecting a hydraulic pressure associated with one of said work functions and determining the maximum pressure for one of said work functions based upon the detected operating parameter. 
     
     
       7. Method according to  claim 1 , comprising detecting an operating parameter which is indicative of a position of the implement and determining the maximum pressure for the work function based upon the detected operating parameter. 
     
     
       8. Method according to  claim 1 , comprising detecting an operating parameter which is indicative of an orientation of the working machine and determining the maximum pressure for the work function based upon the detected operating parameter. 
     
     
       9. Method according to  claim 8 , wherein the actuator comprises at least one hydraulic cylinder for each of the work functions lift and tilt, the method comprising detecting an operating parameter which is indicative of a position of the hydraulic cylinder. 
     
     
       10. Method according to  claim 1 , wherein the hydraulic system comprises at least one hydraulic actuator for controlling each of said work functions. 
     
     
       11. Method according to  claim 10 , wherein the actuator comprises at least one hydraulic cylinder for each of the work functions lift and tilt. 
     
     
       12. Method according to  claim 1 , comprising detecting an operating parameter which is indicative of a load on the working machine and determining the maximum pressure for the work function based upon the detected operating parameter. 
     
     
       13. Method according to  claim 1 , comprising determining the maximum pressure of the hydraulic fluid individually for the work function depending on the handling being performed. 
     
     
       14. Method according to  claim 1 , comprising determining the maximum pressure of the hydraulic fluid individually for the work function depending on the type of implement. 
     
     
       15. Method according to  claim 1 , comprising determining the maximum pressure of the hydraulic fluid individually for the work function depending on the type of implement. 
     
     
       16. Method according to  claim 1 , comprising determining the maximum pressure of the hydraulic fluid individually for the work function depending on a signal from an operator-controlled element. 
     
     
       17. Method according to  claim 1 , comprising determining whether a maximum pressure at a level above a basic level for the maximum pressure is required to the function and temporarily increasing the level of the maximum pressure to the level above the basic level. 
     
     
       18. Method according to  claim 1 , comprising continuously determining whether only a maximum pressure at a level below a basic level for the maximum pressure is required to the function and lowering the level of the maximum pressure to the level below the basic level if only the lower maximum pressure level is required. 
     
     
       19. Method according to  claim 1 , comprising determining a maximum pressure of a hydraulic fluid for performing a certain task with the implement individually for at [east two of the work functions and supplying the hydraulic fluid, pressurized at most to the determined maximum pressure, to each of said work functions. 
     
     
       20. Method according to  claim 19 , comprising supplying the hydraulic fluid, pressurized at most to the determined pressure, simultaneously to each of said work functions. 
     
     
       21. Method according to  claim 1 , comprising actuating the control valve via an electrical signal. 
     
     
       22. Method according to  claim 1 , comprising continuously detecting a hydraulic pressure to the function, comparing the detected pressure with the determined maximum pressure, and interrupting the pressurization of the function when the detected pressure is greater than the determined maximum pressure. 
     
     
       23. Method according to  claim 1 , wherein the hydraulic system comprises a common pump adapted to supply a plurality of said functions with pressurized hydraulic fluid. 
     
     
       24. Method according to  claim 23 , comprising controlling the pump via an electrical signal. 
     
     
       25. Method according to  claim 23 , comprising limiting a maximally modulated pump pressure.